Siultios s ice telephone system



Math 19, 1929. NELSON 1,705,833

MULTIOFFICE TELEPHONE SYSTEM Original Filed Sept. 17, 1923 7 Sheets-Sheet 1 March 19, 1929. M. L. NELSON MULT'IOFFICE TELEPHONE SYSTEM Original File ep 17. 1925 '7 sheets-sheet 2 mm I March 19, 1929. "M. NELSON MULTIOFFICE TELEPHONE SYSTEM 7 Sheets-Sheet 3 Original Filed Sept. 17, 1923 :4 N n E n. E w x mN w mL .1 E M .m a L \QN v E. I 5 m a ..\\N %\N \QN WQ M INF v 13 w, w kw L. NELSON;

March 19, 1929.

' MULTIOFFICE TELEPHONEXSYSTEM Original Filed Sept.1'7, 1923 7 sheets-sheet 4 H572??? LNelsun M L 19, 1929. ,M. L. NELSON 1,705,833

@ MULTIOFFICE TELEPHONE sYsTp Original Filed Sept-11 1923 [Sheets-Sheet March 19, 1 929. I NEL$QN 1,705,833

MULTIOFFI CE TELEPHONE SYSTEM Original Filed Sept. 17, 1923 7 Sheets-Sheet 6 fill um um W" W FL' MM Mnfl llnfln Mun mu Illlllll MM Mary 3mugnunn'gnunnguuun March 19, 1929. NELSON 1,705,833

MULTIOFFICE TELEPHONE SYSTEM Original Filed Sept. 1'7, 1923 '7 Sheets-Sheet 7 a HEFZzTz.

Fatented Mar, 19, 1929.

psi-ran stares artisan Parent. ew s.

MARTIN L. NELSON, or PARK RIDGE, ILLINOIS, ASSIGNOR, BYMEsnn ASSIGNMENTS,

To AUTOMATIC ELECTRIC rnc or CHICAGO, ILLINOIS, A conronATIoN or DELA- WARE.

MU TIorrrcE TELEPHONE SYSTEM.

Application filed September 17, 1923, Serial l lo. 663,058. Renewed September 15, 1928.

The present invention relates to Inulti-olf1ce telephone systems in general, but is concerned more particularly with such multi-ofiice systems as employ directors to route the calls; and the broad general object is the production of new and improved circuit arrangements for the directors and their associated apparatus whereby their various operations are performed in a simpler and more reliable manner. 7

Specifically one of the objects of the pres ent invention is the production of a new and improved vibrating interrupt-er individual to a director for the purpose of controlling the sending equipment. 7

Another object is the production of new and improved circuit arrangements whereby the steppingmagnet of the sending switch, in addition to operating the sending switch in its step by .step movement to. count off the interruptions produced in the outgoing con- "rol circuit, produces the. necessary interrup tions in the outgoing control circuit to control the automatic switches.

Another object is the production'of new and improved circuit arrangements whereby one single skip conductor maybe provided to enable the send'ng sequence switch to skip over any one of the four positions'allotted to the scndingout of the oflice code. Formerly one skip conductor was required for each code digit to be skipped.

Another object is the production of a simplified arrangement for preventing the sending equipment from advancing ahead of the registering mechanism when the calling subscriber is slow in dialling the remaining part of the number. 1

Another object is the production of suitable circuit arrangements whereby the first selector switch is unresponsive to the operations of a subscribefls calling device in case he waits so long before dialling the first digitthat the call has beenswitched through automatically to a first selector in order to free the director for another call. This is to pre-' vent a call from going wild with the likelihood of annoyance to another subscriber, which might happen in case a calling subscriber were permitted to operate the switches, it being understood, of course, that the first part ofthe number is translated by the director. 7

it further object of the invention is the product-ion of suitable circuit arrangen'ients whereby the resistance of the loop through wh1ch automatic switches are controlled by the sendlng equipment of a director is decreased, when a very long inter-office trunk taken for use, in order to secure the proper operation of the remaining switches in the train. i

A still further object is the production of new and improved circuit arrangements whereby the selecting switch which is individual to a first selector trunk and which selects a director when a call is made, is caused to step ahead one step when the director in use switches through and is freed. This is done toinsure an equal distribution of the traffic amongst the various directors and in order to prevent a calling subscriber from gettlng the same'director repeatedly, and thereby be preventedfrom getting service, in case the director in question is out of order.

A still further feature of improvement contained in the present case is thearrangcment whereby, on calls to the toll recording operator,the operator is reached over any one of a plurality of groups of trunks, dependin. upon the kind of service or the extent of a;

service to which the instant calling subscriber is entitled. it Specifically the director is ar lates to the provision of suitable circuit arrangements for cutting in a separate low rc sistance battery supply for the calling line when anexpre'ss call is answered. This a void. the necessity of roviding a separate group oftrunks for giving express service, which can then be given over the same trunks that are used for giving local service.

There are several other'novel features disclosed, having to do mainly with thevarious circuit details employed in carrying out the principles of the, invention set forth above. These features, together with the foregoing,

will be explained fully hereinafter in con- Figs. 4-7, inclusive, show oneof the directors.

Referring now particularly to Figs. 13, inclusive, Fig. 1 shows a. substation A, of

' which the line terminates at the exchange in the line switch C which in turn has access to the selector D, Fig. 2, by way of the repeater R. The repeater'll has an associated individual secondary switch SS which has access to a number of directors of which the one shown. in Figs. 4l7, inclusive, is one.

Fig; 2'shows the selector D, which is individual to the repeater R and whichhas access to a number of second selectors of which one is the selector Eindicated by the dotted rectangle bearing that reference character. Theselector E has access to a number of selectors of which one is the selector F, which selector in turn has access to a number of trunks, of which the one comprising conductors 151and 152 is one. This trunk is a two conductor trunk and it extends to the office in which the express service operator is located, and terminates therein the plug ending cord circuit CC.

In addition to the trunk comprising conductors 151 and. 152, two other trunks are shown accessible to the selector F. It is assumed that the trunk comprising conductors 151 and 152 is one of the group of trunks over which unlimited express service calls are handled. It is assumed that the trunk comprising conductors 161 and 162 belongs to the group of trunks over which calls originat ed by limited; service subscribers are handled. It 'is assumed further that the trunk comprising conductors 171 and 172is one of the group of trunks over which calls originated by subscribers not entitled to any express service are handled. These three group of trunks may all extend to thesanie operators position or they maybe extended to three different operator s positions, depending of course upon the local requirements.

Fig. 3 shows, in addition to the cord circuit CC, the cord circuit CC to which connection can be extended from the cord circuit CC by way of jack J and the inter-office trunk comprising conductors 221 and The ofllce in which the'cord circuit CC is 1002 ted lies beyond .the limit of local service and calls to it are'handled by means of the express service and charges are made accordingly.

Fig. 3 shows alsothe substation B and the associated line which terminates at the exchange in. the ack J, and shows, in addition, the inter-ofiice order wire Ol V, together with the operators head sets at either end, and the push button P. I

Referring now particularly to Figs. inclusive, the portion of the director shown in Fig. 1 comprises the four control relays 3064509, inclusive, and the sequence switch S, together with the four digit register DR1-DR-el, inclusive; the portion of director shown in Fig. 5 comprises the sending switch SEN and the relays 410 and ill, to gether with the vibrating interrupter l12; the portion of director shown in Fig. 6 coinprises the office register OR and the intermediate distributing frame IDF; and the portion of the director shown in Fig.7 com-' prises the relays (3111, 619, 620, 601, and 602, and the sequence switch S.

The line switch C, Fig. 1, is mechanically of the well known rotary type in which the wipers have no-normal position and move in a forward direction only.

The selector D, Fig. 2, as well as the lectors indicated by the dotted rectangles E and F, is mechanically of the well known vertical and rotary type in which the bank con tacts are arranged in horizontal rows or levels. I

The oi'lice register OR of the director, Fig. 6, is mechanically of the same type of switch as the selector D. I v

The sequence switch S, Fig. 4, is mechanically a simple type of switch, having the wipers 338 and 334, which are advanced over the associated bank contacts by the stepping magnet 331, andwhich are restored to normal 7 position upon the energization of r lease magnet 332, whose circuit 1s controlled by oif normal contacts 336. The, mechanicalconnection between the armature (not shown) of stepping magnet 331 and wipers 333 and 33 i is such that the said wi pcrs are advanced upon the back strokerather than upon'the front stroke of the armature. Accordingly it necessary to provide means for energizing thestepping magnet upon the release of in, Y

the wipers in order to pullthe associated pawl switch, having wipers which move in a for-.

ward direction only. The wipers of the switch are advanced upon the deenergization rather than upon the energization of the step- Fig. 5, is meping magnet 40?, which is indicated schematically in the dra 1g. The sequence switch Cl, Fig.7, is mechanically. similar to the sendingswitch SEN. exceptas regards the number ot wipers employed.

The s stem and the a )oa ratus shown hav- 1 L v mg been directed more or less in general, a

detailed description of the operation of the phabet are often placed on the calling devicev inaddition to the numeralsl to 0. It will'be assumed further that the complete number of the desired station is 70O987, the numerals 7 and representing the oi'iice and the remaining part of the numbers signifying the particular subscriber desired in that ofiice.

When the receiver is removed at substation A, line relay'15 oi the line switch C operates over line conductors 11 and 12 and places ground on private normal conductor 13 at armature 22, thereby making the calling line busy to the Connector switches having access to it and also closing a circuit through swithing relay 14 and stepping magnet in series. As a further result of the energization of the line relay 15 it connects test wiper 2% to the junction of switching relay 14: and line relay 2O armature 21.

The further operation depends upon whether the trunk upon which the wipersot the line switch are standing is busy or idle.

Assuming the trunk to be busy, test contact 28 is grounded over conductor 32 and the ground potential is extended through test wiper 2S, armature 17, and its resting contact, and the working contact of armature 21 and said armature to thejunction of switch ing relay 1% and stopping magnet 20. Switching re short circuited by ,this ground potential and does not energize and stepping -ugnet 2O energizes and interrupts its own circuit, thereby advancing the wipers inclusive, step by step until test wiper cu es on ungrounded test contact. in the present case. however, it will be assumed thatthe trunk upon which the wipers ot' the line switch are standing is idle. That being the case switching relay 1% is not short circuited and accordingly energizes in series with stepping ma netQO immediately following the above mentioned energization of line relay 15. Stepping magnet 20, however, is

not energized at this time on account of the high resistance of switching relay 1%. Upon energizing. switching relay ledisconnects test wiper 2% from the junction of its own winding andthat of thestepping magnet 20 and connects it to the grounded private normal conductor 13, thereby preparing a holding circuit for itself and simultaneously making the seized trunk busy. As a further result of the energization'ot switching relay l l it disconnects line conductors l1 and 12 from the windings of the line relay 15 and ground, at armatures l6 and 19, and extends them by way of wipers 23 and 26, bank contacts 27 and 80, conductors 31 and 34, and the normally closed contacts controlled by arma tures 51 and 52 to the upper and lower windings of the double wound line relay H of the repeater Pt. Line relay 44, upon energizing, closes a circuit for release relay 46 at armature 57 which extends through the resistance 4:9 to battery. Release relay do, upon en er izing, places ground on release trunk conductor 32 at armature 60, thereby completing the holding circuit for switching relay 14c of the line switch C before the slow acting line relay 15 has had time to deenergize. As a further result oi the energization of release relay L6 it closes at armature 62 a circuit for the polarizing winding of the el-ectropolarized relay Relay 45, however, does not energize at this time onaccount of the fact thatits polarizing winding is composed of a comparatively small number of turns of wire having a relatively high resistance. 7

As a still further result of the energization of release rel l6 of the repeater R, it closes at armature 61 a circuitthrough armature (39 and its resting contact for switching relay 81 and stepping magnet 82 of the secondary switch SS in series, and at armature Get connects test wiper 91 to the junction of switching relay 81 .and the stepping man 1; 82, hrough the resting contact or" armature (5? and said armature, and the resting Contact. of armature 85 and said armature. lhe closure of these two circuits results in the secondary switchSS selecting an idle trunk in th sa manner as above described for the lint C, and, assuming that the trunk upon X the wipers of the secondary switch are standing is idle, the wipers are not rotated and switching relay 81 energiaes inm'iediately. Switching relay 81, upon energizing, disconnects test wiper 91 from th unction ot' its own windings and those of stepping pwunet 82 and connects it to ground at arniatr thereby making the seized director l)! sy l mediately by grounding to nine 302 through bank contact 9-6. Switching relay 81 also connects up wipers Si 90, 92, and 93 at armaturesSS, 84, 86, and 88, respectively, and at armature 8'? prepares a circuit for stepping magnet 82 wnich will be closed subsequently. v

With vipers 89 and 93 of the secondary switch SS connected up at armatures 83 and 88, respectively, a bridge is placed across conductors 71 and 'l 3 extending from the repeater R to the selector 1), Fig. This bridge in- Elm 7302, a circuit is dialled Cir circuit for release relay 116 at armature 126. Release relay 116 thereupon and L places a multiple ground on release trunk con- .ductor 72 at armature 127 and at armature 128 opens a point in the fllC'dlti ot release mag "net 120 and prepares a circuit tor vertical magnet 122.

in the director, release relay 308 which is connecteddircctly to the conductor v02 ergizes, in response to conductor 302 being grounded through est rip er 91 ot the secondary switch SS as pointed out above, at armatures 317 and 316 removes ground rroiu conductors 353 and 352, these points the restoring circuits oi various mechanical switches oi. the director. Relay 308 also opens the normal restoring circuit of the sending switch SEN, Fl 5, at armature 314i, and at armature 815 connects the common timing conductor 321 to the upper winding of the marginal. two step relay through armature 311 and its resting contact. As a further result of the ground potential being placed on the release trunk condi ClOSf through the resting contact oil armature 121 of start relay 4111, Fig. 5, for the n agnet 112 oi? the individual vibrating interrupter V. Magnet 4-12 thereupon becomes energized and attracts the sociated armature, causing the pendulum l3 to be pulled to the left and remain in this position preparatory to the first sending operation. r

The director now in readiness to receive the desired ni'unber, but, before the dose '1p tion of how the number is received en, the operations involved inswitching the all throiigh to the first s lector D, Fig. 2, in case of at long a wait before the first digit is w'll be described. For this purpose, it will be assunied that the calling subscriber,

having removed his receiver with the above described results, fails to dial his number right away, and instead turns to other bu i ness, leaving the receiver oil the hook. 1n this case, if it were not for the special proisions that are made, the director would be tied up ii'uleiinitely. 'lhe wayin which this is prevented will now be described. As soon as ground isplacta'l upon the common conductor llig. '1, by the springs controlled by the cam who 310, after the energization of release relay 308, a circuit 1s closed through armature 811 and its resting contact for the upper winding of the marginally adjusted two step relay 306. Pielay 306 energizes at this time only far enough to bring armature 312 into engagement with its associated contact but it does not operate thereby opening at armature 311. Armature 312 by coming into engagement with its associated contact locks relay 306 to the; grounded release trunk con ductor 302 through the lower; winding of the said relay. This locking circuit is not effective to energize the lower winding" of the relay this time owing to the fact that the said winding short circuited by the ground potential which is applied through armature S11 and its resting contact.

hen ground is subsequently removed from the common conductor 321 the initial circuit of the upper winding of relay 806 is broken and the circuit for the two windings of the relay in series becomes effective, whereupon the relay operates fully and armature 311 is brought into engagement with its '7 working contact, thereby preparing a circuit for switching relay 309, which includes conduct-or 851, off normal contacts 500 of the o'llice register OR, switching conductor 354,

and the normally closed contacts controlled Fig. i, again operates its contact springs,

thereby elacing ground on conductor 321 which results in the above taced circuit. throu h armature 311 and its working contact ror switching relay 309 being'closed. Switching relay 309 thereupon energizes and locks itself to conductor 302 armature 319, at the same time opening its initial circuit. As a further result of the energization of switching relay 309 it opens the incoming impulsing circuit, which includes series r elay 307, at armature 818, and closes a circuit "for switching relay 4-8 of the repeater R as follows: from ground by way of resistance 63S associated with relay (301, 7, conductor 360, working contact of armature 818' and said armature, conductor 303, bank contact 97, wiper 92 of the secondary switch S8, arn'iatnre 86 and its working contact, armature '58 of line relay anc its working contact,

marginal relay l7, and the upper winding of switching relay 18 to battery. Switching relay 1S energizes over this circuit, but relay 4-7, being mar inally adjusted, does not enerou 'oi lL- ot the inclusion of resistance (338, Fig. 7, in the circuit. Relay 48, upon energizing, places at armatures 71 and 73, a second bridge across conductors 71 and 73 in multiple with the one already closed in the director. This second bridge includes the lower winding of the electro-polarized relay and the right hand winding of the impedance coil 50. Eleetropola-rized relay 15 does not energize responsive to the closure of his bridge owing to the fact that the current 7 fiowthrough its lower winding is in such a direction as'to set up lines of force 1n opposition to those produced by the current fiow in the upper winding.

As a further result of the energization of switching 'relay48, it opens the circuit of the slow acting switching relay 81 and closes a locking circuit for itself at armature 69. This locking circuit includes the'working contact of armature- 61 of release relay 66 and its resting contact and lower winding of relay 48. The opening of the circuit of switching relay 81 ofthe secondary switch SS results in the deenergization of said relay 81 after an interval. During this interval a circuit isjclosed in multiple with the lowerv winding of relay 48 and through armature 87 of the said relay 81 and its Working contact for stepping magnet- 82. Stepping magnet 82-, accordingly energizes, but, owing to the fact that the associated wipers areadvanced only on the back stroke of said magnet, the Wipers are not advanced at this time 7 and the pawl of the armature of the magnet 82 (not shown) is merely moved into engagement with another notch on the ratchet wheel which drives the associated wipersf After a momentary interval, switching relay Sllels go, thereby freeing the director, and

at the same time opensthecircuit of stepping magnet 82, whereupon the w pers 8993, 1n-

. elusive, are advanced-into engagement with the next set of bank contacts. This is the hereinbefore mentioned expedient employed 7 to insure that two successive calls over the same trunk do not take the same director for use unlessall the others happen to be busy. Asa result of the deenergization of the switching relay 81, the previously traced bridge across conductors 71 and 78 in the director is opened atarmatures and 88, leaving the line relay ot the selectorD energized through the'hridge which is now closed and 73, in the repeater R,

48. In the repeater R, switching relay 48 also separates conductors 101 and 102 at armature 70. thereby opening the circuit of the vertical magnet 122 of the selector 1) so as to prevent the switch from being, operated in, case the calling subscriber later returns to the phone and starts to manipulate his calling device before first replacing his receiver long enoughto break down the connection and the selector D. r I

, As above pointed out,'the director, which is a comparatively expensive organizationof equipment. is freed and the call is switched through to the selector 1) where it will soon be detected as a permanent by an. attendant who'is notified of the conditionby means of the usual supervisory equipment (not shown) associated with the selector D for that purpose. The expression permanent, it will be between'his line understood, is the term ordinarily applied to the above explained condition wherein no the deenergization of magnet 412 of the vi-- brator V results in the release of the associated pendulum 413 whichstarts to ibrate, and on each outward swing, closes the contacts 414. This does not cause any harm to result, however, owing to the fact that start conductor 859 is not grounded at this time and the vibrator V presently comes to rest,'after about thirty or forty vibrations. I

It will now be assumed that the subscriber at substationA, in making this call, does not wait undulylong before dialling, as was assumed in the case. just described, but that, after having removed his receiver with the result described hereinbefore, he listens for the dial tone andthen proceeds to dial as soon as he hears it. The dial tone, it may be mentioned, is placed on the impulse conductor by the dial tone transformer 505, Fig. 6. The tone induced in the right hand winding of the transformer 505 passes through the vertical said armature, conductor 303, bank contact 97,

wiper 92, arma ture 86' and its working contact, armature 57 and its working contact, condenser 74, resting contact armature 71 and said armature, and thence byway of the lower heavy talking conductor to the substation A. The.calling'subscriber, upon hearing the distinctive tone produced in his receiver by this 1 current, knows that sired number.

- Vr hen the calling subscriber manipulates h calling device in accordance with the first oti'ice digit. 7, a corresponding number of interruptions are produced in the circuit of line relay 44 of the repeater R, resulting in seven momentary deencrgizations ofthe said line relay 44. Upon each of these deenergizations he may now call the dcline relay 44 short circuits release relay 46 at armature 57. However, as is well known, 'a'relay short circuited inthis manner has the characteristics of a slow acting relayand is even more constant in its tendency to maintain its armature attracted for an interval than if it were provided with acopper collar I and its'circ'uit merely opened. Accordingly, release relay 46 is not deenergized but maintains its arn'iature attracted through the series of'deenergizations ofline relay 44." Asa further result of each deenergization' of line the entire series of impulses.

relay 44, it disconnects the combined impulse and switching conductor from switching relays '47 and 48 and connects it to ground at armature 58 thereby com aleting a circuit for 7 v Q vertical magnet 504 of otlice register OB, Fig. 6, whichextends from ground through the resting contact of armature 58 and said armature, working contact of armature 86 V and said armature, wiper 92,,bank contact 97,

conductor 303, armature 318 and its resting contact,ser1es relay 307, wiper '333 ot the sequenc switch S, the first associated bank contact, conductor 337, vertical magnet 504,

and the right hand winding of the dial tone transformer 505 to battery; By the operation of vertical magnet 504, which is energized each time the'above circuit is closed, the wioers 511514, inclusive, of the ofiice register are raised step by step until they stand opposite the seventh level of bank contacts. Relay 307 is energized in series with vertical magnet 504 upon the first energization of the latter and, being slow acting, maintains its armature attracted throughout Upon energizing, relay 307 closes at armature 313a circuit for stepping magnet 331 of the sequence switch S. Stepping magnet 331, upon which are the four contacts indicated energizing, does nota'dvance the wipers 333 and 334 but merely makes ready to advance them when it is subsequently deenergized.

the said-magnetdeenergizes with the result that the wipers 333 and 334 are advanced into engagement with the next set of associated bank contact a i The calling subscriber may now operate his calling device in accordance with the second oiiice digit 0,'resulting in a series of ten impulses of the current being sent to the rotary magnet 503 of the o'ffice register OR over the circuit previously traced for the vertical magnet 504 as far as wiper 333 of the sequence switch S, Fig. 4, and from thence by way of the second associatedlbank contact and conductor 338. As a result, rotarymagnet 503 energizes ten times andadvances the wipers 511-514, inclusive, into engagement with the tenth set bank contacts in the seventh level as in the drawing.

Series relay 307, Fig.4, at this time ener-' 'giz'es as before 'ClGSOl'lbGtl, resulting in the wipers ot' the sequence switch S being advanced into engagement with the third set of associated bank contacts. Wiper 334, upon the operation of the sending equipment with the results which will be explained hereinafter. r I

The calling subscriber may now manipiu late his calling device in accordance with the first subscriber digit 0, resulting in ten impulses ot current being delivered over the above traced circuit to wiper 333, and thence by way of the third ass ciated bankcontact to the first digit register DR'1. The wiper- 343 of the digit register DR1, accordingly advances into engagement with the tenth associated bank contact. I

At the termination of the operation oi the digit register DR1, thewipers of the sequence switch S are advanced, and 'in the same manner as described for digit register DR1, the digit registers DR-2, DR3 and Dirt-4 are set, the wiper of the digit register DR2 being set upon the ninth associated bank contact, the wiper of the digit register DR3 upon the eighth associated bank contact, and the wiper of the digit reg ister DR4 upon the seventh associatedbank contact.

At the termination of the setting 0t digit register DR-4, wipers 333 and 334 of the sequence switch S are advanced into engagement-with the seventh set of associated bank contacts in which position they remain until the director is released.

The operation otthe sending equipment, which is started,as above pointed out, at the termination of the setting of the otfice register OR, will now be taken up. When ground is placed upon start. conductor 357 .by wiper 334 of the sequence switch S, a circuit is 7 closed through the first'contact in the bank.

ot' wiper655 of: the sequence switch S, Fig. 7, wiper 655, conductor 359, resting contact of armature 419 and said armature, and start relay 411 to battery. Start relay 411, upon energizing, prepares a locking circuit for stop relay 410 at armature 420, and at armature 422 places ground, through armature 418 and its resting contact, on conductor 407, thereby closing a circuit for stepping magnet 651 of the sequence switch S, Fig. 7. Stepping magnet 651 now energizes,"whereupon the associated pawl is moved-into engagement with the next notch on the wiper driving ratchet Wheel, but the associated wipers 6534556, inclusive, are not operated. As a further result of the energizat-ion 0t start v relay 411, it opens the circuit of magnet 412 of the vibrator V, whereupon the said magnet :denergizes and trees the pendulum 413 which start-sto vibrate at the proper rate for sen ding out the sw tch control impulses,

Each time the contacts 414 are closed when the pendulum 413 swings away from the mag- 7 net 412, a circuit is closed from the grounded tracted, resulting in the Wipers 401 and/102' being advanced onestep.

As a further result of each energization of stepping magnet 103, it opens the bridge across conductors-301' and 305 at contacts 104, and consequently opens the circuit of line relay 115 of the selector D, with the result that the selector D is operated in a manner to be explained subsequentl Since the first'digit to be sent out is the digit 3, the vibrator V continues to vibrate and the wipers 101 and 102 of the sender SEN continue to be advanced step by step by the operation of stepping magnet 403 under the control of vibrator V until the three impulses have been sent out, at which time wiper 402 arrives upon the fourth associatc-d banli contact which is the contact in which the third impulse stop conductor terminates; At this time a circuit is closed tor-stop relay 410 oi tee sender SEN follows: from ground by way of the stop.

conductor control wiper 654 of the sequence switch S, the first associated bankcontact, the first oihce digit stop conductor 521,, *iper 511 of theoiiice register OR, the bank contact upon which the said wiper 511 isstanding, conductor 541, the associated jumper on the intermediate distributing frame lDF,

- the third impulse stop conductor 583, the

fourth. ,contactin the bank oiwiper 102 of the sender SEN, Fig. 5, wiper 102, and

stop relay 4:10 to battery; Stop relay 410 now energizcsto terminate the lust oiiice code digit 3, and disconnects start relay 411 from start conductor at armature 41S), leaving the circuit of relay 111 closed through 'iper 101 and the grounded. bani; contact upon which it standing 7 Stop relay'liO also opens the circuit of stepping magnet 651 of the sequence switch 5" atarmature 4-18, whereupon stepping mag not 051 deenergizes and the wipers 01' the sequence switch are advanced one step. I

As a further result of the energization oi stop relay 110 it closes at armature 418 a holding circuit for magnet 412 of the vibra tor V, whereupon magnet 412 becomes energized again and attracts andholds the pendulum 2-312 preparatory to the next. series of impulses to be produced at contacts 414;. As alfurther result of the energization of sto relay 110, it connects wiper 101,. which is now standing on a grounded bank contact,

with stepping magnet 403 at armature +t-15 -erupter contacts 405, and at )l ces a shunt around inter- 0 1 so as to prevent their a i sequent 0} the switch control circuit. Responsive to the A n oi armature 1-15, stepping magnet 1-03 o Hates in tee manner oi a buzzer and 11102 the w pers 101 and 4-02 step by step until they n reach th ir n rr al position at which til -e W136i 101 is in enga ement with an un grounded bank contact, resui ing in the openingot the circuit of stare relay 111. relay L11, however, being slow acting does not deenergize immediately. 7

in the selector D, Fig. 2, each time 1' ie relay 115 deonergizes in response to the rice or three interruptions produced in its circuit in the director as hereinbei ore described,it closes circuit for vertical magnet 122 as follows: from ground by way oi the resting contact of armature 15 nd said armature, cure 126 and its resting contact, armature 128 and its working contacts, series relay 117, conductor 102, armature 70 and its resting contact,conductor 101, and vetical magnet. 122 to battery. Since line relay 115 is deenergized threetiines, this circuit is closed three times and vertical magnet 122 op rates to raise the wi 136-13 8, inclusive, step by stop until they stand opposite the third level bank contacts. Relay 117 is energized in series with vertical magnet 122 upon the first impulse of current being delivered to the latter and, being slow acting, maintains its armature attracted throughout the vertical movement. By the joint action whi close upon the first vertical step, a circuit is completedi rom the. grounded release trunk conductor- T2, through armature and its working contact, 'oi'i' normal springs 135, and interrupter contacts 124; for

stepping relay 1153. Upon energizing, steprelay 118 closes a locltine' circuittor itl at armature 130,-and at urina v 131. prepares a circu t rota! y magnet 1223.

tile end oi th' v real movement, series why 11'! dcencrgiucs and completes a armatui 2:) a. circuit to ,lary magnet 12 liotary magnet 123 thereupon energ zes and advances wipers 136 138, inclusive, to engagement with the first contact in the level opposite which they are now standing and. near the end of its stroke, opens the circuit of steppin relay 118. Stepping relay 118 accord ingiy deenergizes and-opens the circuit of rotary magnet 123 at armature 131, whereupon rotary magnet 123 dcenergizes'also and again closes its interrupter contactsl2d.

'f e further operation depends upon whether the trunk terminating in the first set bank contacts is busy or idle. Assuming that it is idle, Witching relay 119 energizes right away and switches the 'connect-ion throughto the trunk. In case it is busy,

eration rroin interferring with opens the circuit of the wipers acvanced into en energizes again with however, switching relay 119 is short circuied by the ground potential encountered on he busy test contact by test wiper 137 and does not-energize. Stepping relay 118, however, is energized by this same ground potential and again closes the circuit of the rotary ma st 125, whereupon the switch the next 'et oi bank ibis alternate operation oiistepping relay 118 and rotary magnet 123 continues, described unt i. an idle trunk s reached which trunk it will be assumed is the one terminating in bank contacts 1381M, inclusive. 1V hen such idle trunk is reached, switching relay 119. being no longer short circuited, energ Les in so; with stepping relay 1-18. Steppi g relay 118, however does not energize at Mrs time on account of the high. resistance of switching relay 119. Upon energizing switching relay 119 removes ground iroin miniature r20 line relay 115, at armature 13-1, thereby opening; the circuit of the slow acting release relay 116; disconnects test wiper 137 from the junction oft its own winding and that of stepping relay 118 and connects it to the ground-- ed release trunk conductor C 2 at i ature 152-3, thereby making the seized truni; busy iu'unediately and preparing the lKElCl'iRQ' circuit; and atarinatures 132 and 135disconnects talking conductors '71 and i2) from the windings of line relay 115 and exteudstheni by way otwipcrs 13S and 138. bank contacts 139 and 14:1, and the associated talkin conductors to the associated,selector "E (which is denoted by the dotted rectangle bearing that referent-e character). The line and rerelays (not shown) of the seized selecior now energize in the usual manner and the latter prepares the switch for operation d places the usual p round potential upon the associi ,ed release trunk conductor.

Returning: now the direction the slow acting slartrelay 4 11 of the sender. Fig. F, de-

zse: after an interval and at armature slow acting stop relay 410 and at. armature places a shunt around armature 4:18 and its worhin fitter an interval slit-w acting;

The interval required for the relays 111 and 4110 to fall back one after the, other, as described. is utilized by the selector D. as described above, in effecting the changeover and trunk hunting; operations.

When the circuit of the start relay 411 is again closed at arniiature e19 by relay 19,, it the above pointed out results including the openin of the circuit of magnet 412 of ill rater V. The vibrator V again operates to intermittently close the i-ontacts 41 1 thereby driving); the sending);

s itch SEN around step by step through the medium of the stepping magnet 403 which oihce register OR, the bank contact upon which it is standing, conductor 5-12, the associatcd IDF jUiIlpO'i,1liG third impulse stop conductor 58? the tourth contact in the bani: of wiper 102, of the sending switch wiper 02. and stop relay 1:10 to bate The resulting ener 'ization of stop relay 1:10 terminates the second oflice. code digit 3 in the here'inbetore described manner and aci of stop con-;

cor line'ly opens the circuit oi stepping inagnet 51 of the see ience switch S whereupon 1 wi ers of th said sequence switch are adwinced into engagement withthe third set of bank contacts.

The advance of the wipers. of the sequence switch S onto the thirdi-set of bank contacts.

results in ground being placed upon the third digit stop conductor 5231) the stop conductor control wiper 654. A circuit is thereupon closed ever stop conductor 523, wiper 513, the bank contact pen which 'it is standing, conductor 13, the associated ll)?" juniper, skip conductor 510, interrupter (3011-,

tacts :2 and stepping inagnet 651'to battery. Stepping magnet 651 is accordingly 01 erated tointerrupt its own circuit at contacts 652, r sulting in the wipers of the sequence switch being; advanced into engagement with the. set oi bank contacts.- This results in iourth ground being placed on theftourth oiiice digit stop conductor 324: by i ti ol wiper {35 5- closiupgja circuit over conducs standing, conductor 544- theiissimialied jumper, and thence as above traced for the step iin s; ua t 351 of the sequence switch C. 'lhc step hip; magnet 651 is again operated and 7 contacts (3532, resulting in the wipers of the sequence switch being advanced into engagement with the next set of bank contacts. 1

The above described operations of the se ($301168 switch 5% have occurred in a very small traction of a second and are completed long before the sender is in position to transinit the next die-it which is thefirst digit 0 in the stop conductor con-5 interrupts its own circuit at the subscriberjs number,*the office code 33 having been transmitted as described above.

0nd, or even the first code digit, as well as the third and fourth, as pointed out", In fact, in case it is so desired, all four of the code jumpersmay lead to the skip conductor in which case the skipping il'Ocess begins immediately upon the grounding of start conductor and the firstdigi-t'sent out is the first subscriber digit registered. This situation ..1nay arise in some cases where a plurality of levels of the first selectors, say nine, are used toobtain access to the local hundreds selectors,and access tothe other oiiices of the system is gained throu h the remaining level orlevels, of the first selectors In'response to the transmission of the second otiice d git 3, the selectorwh ch was seized by the selector D in response to the .firstoffice digit 3, raises its wiperto the third level and seizes a'trunk extending to the ,de-

sired oiiice, and terminating in an incoming thousands selector. Y

As pointed out hereinbefore, the sending out of theofiice code was initiated responsive to the placing of ground on start conductor 3 57,'by wiper 354 of the sequence switch S and, it will be remembered, occurred after the second ofice digit had been, registered.

' The start conductor 357, it will be noted, is

connected withonly the first four contacts in the bank'of the start conductor control wiper (555 of these uence switch S and accordin ly the ground on startconductor 357, is not Gl'lQCilVQ in again startmg the sender after the sequence switch S has moved beyond the :t'ourth contact, as it has already done. The start ng of the sending'mechanism for the remaining digits in the number is controlled by the digit registers DR1DR4,- mclu- 1 sive. by means ofiwhich thefour subscriber digits of a number are registered. It is obvious that a. digitcan not be sent out before it is received, and accordingly the sending mechanism must not be again started until the first digit register DR'1 has been operated. In known director systems, a pair of off normal contacts areprovided for each digit register, which in connection with a slow acting relay in series with the operating magnet ot the digit register, control the starting circuit tor the sending out of that digitJ (the slow acting relay vis provided to hold the circuit open after the associated off 1 norniai contacts are closed and until the complete digit is re istered in order to insure a b 9 that the sending mechanism does not start so,

quickly that it may overtake the, register betore it has completed its operation.

The present invention provides a new and improved method for controllingthe starting circuit, whereby the above mentioned relays are done away with and the register ofi normal contacts alone control the starting ground. The first register switch, does not exercise any control over the starting circuit and the sender started to send out the first closing its off normal contacts.

subscriber digit responsive to the second digit register moving from its normal position and 7 Then, since it must send out the first digit beforeit can start sending out the secend one, there is no danger-oi the sender overtaking the second 'Wiper 346 of the fourth digit register DR4 moves oif normal and this groundis extended to the seventh and eighth contacts in the bank of wiper 655 of the sequence switch S. It is apparent from the above explanation that in case a calllng subscriber does not dial the first subscriber digit immediately after completing the dialling of the two ofiice digits, the retransmission is held up upon the termination of the ofiice code and the sender is not again started until conductor 361is grounded responsive to the calling of the second subscriber digit. It is also apparent that the same occurs in case the subscriber waits between the calling ot the first subscriber. digit and the second subscriber digit. The same rule applies to the retransmission of the third and fourth subscriber digits.

In the following description it will be assumedthatthe subscriber does not hesitate, but having once started, completes the dialling of his number without waiting more than the usual time between successive digits,

in which case it is quite obvious that the 'director does not catch up on account of the fa ct that it must wait until the first two digits are registered before it can start to retransmit.

The stop conductor control wiper 654 is now in engagement with the bank contact in which the first subscriber digit stop conductor w363 terminates. Ground is accordingly extended over conductor 363 to Wiper 345 of the first digit register DR-1, which wiper is in engagement with the tenth bank contact. This contact is left dead owing to the fact that it is not necessary to multiple the tenth impulse stop conductor to the digit registers or to the intermediate distributingframe on account of the fact that the correspondmg contact in the bank of wiper 402 of the sending switch SEN is permanently grounded, there being no necessity for sendin more than ten impulses in any one series. Kccordingly, when the sender starts to operate to send outthe first'subscriber digit 0, it con-' ten, steps, at which time it encounters the tinues its'operation until wiper 402 has taken above mentioned permanently grounded contact in its bank and stop relay 410 isener gizedwith the hereinbefore described results. The sequence.switch S is accordingly operated to advance its wipers into engagement with the next set of bank contacts, whereupon the stop conductor control wiper 654 grounds the second subscriber digit stop conductor 364. v

The second. digit register DR2 having been-set upon the pi th bank contact, the secondsubscrib'er digit 9 is terminated when stop relay 410 energizes over the following circuit: from ground by Way of the stop conductor control wiper 654 of the sequence switch S, the second subscriber digit stop conductor 364, wiper 3.44 of the second digit register DR2, the ninth associated bank contact, the ninth impulse stop conductor, the

corresponding contact in the bank of wiper 402 of the sending switch SEN, wiper 402, and stop relay 410 to battery.

At the termination of the transmission of the second. subscriber digit 9, the wipersof the sequence switch S are moved into engagement with the seventh set of bank contacts, and aftcr'the eight impulses of the third subscriber digit 8 have been transmitted, stop relay 410 is energized over the following circuit: from ground by way of stop conductor control wiper 654, the seventh associated'bank contact, the third subscriber digit stop conductor 365, wiper 345 of the third digit register DR-3, the eighth associated bank contact, the eighth impulse stop conductor, the corresponding contact in the bank of wiper 402 of the sending switch SEN, wiper 402-, and stop relay 410 to battery.

' After the usual interval following the termination of the third digit 8, the fourth digit 7, is transmitted in the usual manner and is terminated upon the 'energization of stop relay 410 over the following circuit: from ground by way of stopconductor control wiper 654 of the sequence switch S, the fourth subscriber digit stop conductor 366, wiper 346 of the fourth digit registerDR-4, the seventh associated'bank contact, the seventh impulse stop conductor, the corresponding contact in bank of the wiper 402 of the sending switch SEN, and thence to battery by way of wiper 402 and stop relay 410. Upon the energization of stop relay.

I 410, the interruptions being produced in out going control circuits are terminated in the usual manner and the circuit of stepping magnet 651 of the sequence switch S is opened, whereupon the wipers of the said sequence switch S are advanced into engagement with the ninth set of bank contacts and wiper 656 closes a circuitfor switching. relay 409, Fig. 4, as follows: from ground by way of ninth contact in the bank of wiper 656 of the'sequence switch S, wiper 656, switching conductor 354, normally closed contacts controlled by armature 319 of switching relay 309, Fig. 4, and relay 309 to battery. Relay; 309, upon energizing, opens its initial circuit and closes a locking circuit for itself atarnzature 319,- and at armature 318 disconnects conductor v303 from the operating circuit and connects it to the conductor 360, which isgrounded through resistance 638, Fig. 7. This latter operation results in the energization ofswitching relay 48 of the repeater R over the previously traced circuit. Switching relay 48, upon energizing, unites the two sections of the trunk at armatures 68 and 71, and at armature 69 opens the circuit of switching relay 81 of the secondary switch SS and C0111- pletes' a locking circuit for itself through armature 66 and its resting contact, and at the same time, closes the previously traced circuit through armature 87 an-d'its working contact of switching relay 81 for stepping magnet 62 of the secondary switch SS. Accordingly, when switching relay 81 eventually lets goand frees the director,stcpping magnet 82 decnergizes and advances the as sociated Wipers into engagement. with the next set of bank cont-acts. 7

In thedirector, release relay 308 deener gizes responsive to the removal of the ground potential from release trunk conductor 302 I when it is freed in'the above described manner, and disconnects the common lead 321 at armature 315, at the same time closing the three restoring circuits of the director at armatures 314,316, and 317. Armature 314 and its resting contact, it will be noted,'are connected through conductors 35 5 and 356 in multiple with armature 415and its working contact, of stop relay 410 of thesender SEN. This circuit is provided to restore the sender SEN to normal in case the director is freed while the sender is not in normal position.

Responsive to the placing of ground upon conductor 352 by armature 316, of release relay 308, Fig. 4, a circuit is closed through the bank of wiper 653 of the sequence switch S and said wiper, and interrupter contacts 652 for stepping relay 651 of the sequence switch S. Stepping magnet 651 thereupon interrupts its own circuit and advances the the release magnets of the remaining digit registers DR-2-D R-4, inclusive. Accordingly the wipersof all these switches are restored to normal position in the usual manner. The director is now completely restored to normal and is ready to be used ina subse* quent call. i

Returning now tothe established connec tion, it may be pointed out that the desired subscriber is, or course, signalled automatically, and when he responds the conversation may be carried on in the usual manner. 11niuediately upon theresponse of the called subscriber the current flow is reversed in the establishedconnection in the usual and well known manner, and as a result, the two windings of the electro polarized relay 5 .5, of the repeater R, assist each other in energizing the relay. Upon energizing, relay e5 closes a circuit at armature 59 for relay 4C1. Relay 41, upon energizinginserts the left hand winding ofimpedance coil in the bridge across the talking conductors at armature 53, so as to improve thetallring circuit, and at armatures 51 and 52 reverses the direction of the current flow in the calling line. This latter operation does not have any particular utility in the present case, but may he used whenever and. wherever desired for giving supervision to calling PBX operators, or for operating calling subscribers meters and the like.

hen the calling subscriber replaces his receiver at theend of the conversation, the circuit of line relay 44 of the repeater R is opened. Line relay 44: thereupon deenergizes and opensthe bridge across conductors 71 and 78 at ature 35, and at armature 57 opens the initial circuit of release relay 46 1 and places a short circuit around the said relay. After an interval the slow acting re' lease relay 16 deenergizes and opens the circuit of switching relay 48 all-armature 61, whereupon switching relay 48 deenergizes with'the results that'are apparent. As a further result of the deenergization of release relay 46, it removes ground from release trunlr conductor 72 at armature 60, resulting in the deenergization of switching relay 141- of the line switch C and switching relay 119 of the selector D. The deenergization of switching relay 119 of the selector D results in the closure of the circuit of release inagnet 120 at armature 134. This circuit includes armature 126 and its resting coiitact, armature 128 and its resting contact, and oil normal contacts 121. Release magnet 120 uoon ener 'izin restores the selector 1) to normal in theusual manner. The entire connection. 1s now released'and the apparatus involved is ready to be used in another call.

in office 80. It will be assumed further that one of the trunks that must be taken into use when this office is called is exceptionally ninth impulse stop conductor in the special set which is used only when the associated digit is such that the selector which it 0perates seizes an extra long trunk.

In this case, as before, it will be assumed that when the subscriber at substation A removes his receiver, a connection is extended through the line switch C to the repeater R,

and thence by way of the secondary switch SS to the director shown in Figs. l7, inclusive. Then, when the subscriber manipulates his calling device in accordance with the o'liice digits 8 and 0, the wipers 511514=, inclusive, of the otfice register OR are brought into engagement with the tenth set of bank contacts in the eighth level in the usual manner and ground is placed upon start conductor 357 by wiper 38% of the sequence switch S, resulting in the sender SEN, Fig.

a, being started in the usual manner to send out the otiice code. The digit registers DR lDR-a-i inclusive, are operated hereinbefore described, and set up the number of the desired subscriber, whatever that number might be. I

The first three digits 3, l), and 5 ol' the ofiice code are sent out in the usual manner, but when the wipers 6534556, inclusive, of the sequence switch S are advanced into engagement with the fourth set of bank contacts at the end of the transmission of the third code digit 5, the stop conductor, control wiper 654i applies ground to the fourth office digit stop conductor 52- in the usual manner,

thereby con'npleting a circuit through wiper 514 of the oliice register OR, the bank contact on which it is standing, conductor 53%, the associat d jumper, the ninth impulse stop conductor inthe special set of stop conductors, the normally closed contacts controlled by the left hand armature of the two-step relay 619, and the left hand winding of relay 619 to battery. The left hand windingof relay 619 comprises arelatively small number of ti of wire having a comparatively high res ance, and for that reason, is not able to operate the relayt'ully. The contacts on the relay marked 1 are operated at this time, while the contacts marked 2 are not operated, this differentiation being taken care of by the spring adjustment in the usual man ner. At its inner right hand armature, relay 619 locks itself to the grounded conductor 302. This locking circuit is not effective at this time, however, owing to the fact that the right hand windingis short circuited by the 7 quently started, has sent out nine impulses in this digit, wiper 4:02 comes into engagement with the bank contact in which the ninth impulse stop conductor terminates, thereby completing a circuit as previously traced to the left hand armature of relay 619 and thence by way of the ninth impulse stop conductor, the corresponding contact in the bank of wiper 102 of the sender, wiper 402, and stop relay 410 to battery. The resulting energization of relay 410 causes this digit to be terminated in the usual manner and also causes the circuit of stepping magnet 651 of the sequence switch S to be opened, whereupon the associated *ipers are advanced another step, thereby opening the previously traced circuit for the left hand winding of relay 619. l Vhen this occurs the locking circuit through the right hand'winding of said relay becomes effective, whereupon the relay pulls up all the way, thereby disconnecting thejunction of its two windings from the associated impulse stop conductor at the normally closed contacts controlled by its left hand armature, and placing a shunt around resistance 637 in the outgoing loop at its right hand armature, so as to compensate for the extra length of the trunk line assumed to be taken into use by the selector operated in response to the oflice digit which is sent out. I

The subscriber digits of the number are retransmitted in the usual manner, the total loop resistance being about the same as the average, regardless of the extra long trunk taken into use, on account of the above'mentioned elimination of resistance 637, Fig. 7.

In order to explain the feature of the invention having to do with the notification of the toll recording operator of the class to which the calling subscribefis line belongs, it will now be explained how a connection is extended to the toll recording operator. As has been briefly mentioned before, the calls to the toll recording operator are automatically sorted by the director and then sent in over three different groups of trunks depending upon the class to which the calling line belongs. This necessitates the sending out by the director of three different codes, all responsive to the calling of the toll recording operator. It has been assumed that these three codes are 292,293, and 290, 292 being the code used for unlimited service, 293 be.- ing the code used for limited service, and 290 being the code used for the class of lines not entitled to any long distance service. It has been assumed that the toll recordin operator ing line and it may remain normal; pull halt way up; or pull all the way up. When the relay remains normal, as it does when an unlimited service line is calling, conductor 506 remains connected through armature 636 to conductor 507, and when relay 602 pulls all the way up, as it does when a limited serv- .ice line is calling, conductor 506 is'disconnected from conductor 507 and is connected to conductor 508 instead, and when relay 602 pulls part way up, conductor 506 s disconnected from conductor 507 but is not con-H nected to conduct-or 508, thereby automatically causing the digit 0 tov be transmitted when the sequence switch S arrives in the proper position.

Assuming now that the subscriber at substation A, whose line it is assumed is an un limited service line, desires to call the toll recording operator, and assuming further that the line switch C seizes therepeater R, and that the secondary switch SS seizes the director shown in the drawings, the calling subscriber dials the number 60 of thetoll recording operator, resulting in the wipers 5114314, inclusive, of the office register OR being set upon the corresponding bank contacts. Since the calling line is an unlimited service line, and since armature 18 of theassociated line switch C is consequently not connected up,the discriminating relay 602, Fig. 7, of the director is accordingly not energized. Then, after the director has sent out the first two code digits 2 and 9 in the usual manner, the wipers of the sequence switch S are advanced into engagement with the third set of bank contacts and ground is placed on the third wiper of the oflice register OR. Then, when the sender is again started and two interruptions in the outgoing control circuit have been produced, a circuit is closed for stop relay 410, Fig. 5, as follows: from ground by way of the stop conductor control wiper 654 ofthe sequence switch S, the third associated bank contact, the third codedigit stop conductor 523,

wiper 513 of the oilice register OR, the bank contact'on which it is standing, the associated l DF jumper, conductor 506, armature636 of relay 602 and its restingcontact,conductor 507, the associated jumper, the second impulse stop conductor, the correspondingcontactin the sender bank, wiper 402 of the sender SEN, and stop relay- 410 to battery. The energization of-stop relay 410 results in the third code digit 2 being terminatedin the usual manner, and also results in the usual advance of the wipers of the sequence switch Upon being advanced, stop conductor control wiper 65 1 otthe sequence switch S places ground on the fourth wiper 514 of the oliice register OR, thereby extending a ground 'potentialthrough the bank contact on which the said Wiper is standing and the associated jumper to theswitch ngconductor 603, and thence by way of the tourth contact in the bank of wiper 656 of the. sequence switch S, switching conductor normally j closed contacts controlled by armature 319,

out.. 5

Elf the line i to the class not entltled to long distance and relay .309 to; battery. Upon the "energr.

zation of switching relay- 309,'the. connection is switched-through and thedn'ector s need and reverts .to common use in the usual If it is assumed for the moment that the line of substation A is a limited service line,

then the upper terminalof the resistance 9, associatedwith theline switch C, 1s connect= 'ed to armature 18. Then, assuming that the subscriber at substation A is calling; that line switchC has selected the repeater R and that the secondary switch SS has selected the director shown, a circuit is completed'for relay 602, Fig. has-follows: from ground byway of .the upper terminal of resistance 9, Fig. 1, the associated jumper, armature 18 and its Working contact, wiper 25, bank contact 29, conductor 33, working contact of armature at and said armature, wiper90pf the secondary switch SS, bank contact 95, conductor 301, and relay 602, Fig. 7, to battery. Relay 602 accordingly pulls all the way up and disconnects conductor 5061"rom.

conductor 507 and connectsit to conductor 508, which is connected by means of ajumper to the third, impulse stop conductor. liccordingly the limited service code 293,'1nstead of the unlimited service code 292 is sent of the: substation A belongs service at'all, ar1nature18 of the line'switch G would beconnected to thelower terminal of the resistance 9', and, in that case, it the line were calling and if thedirectors shown were used, relay 602 would pull up only half way and neither conductor 507. nor. 508 would be connected to conductor 506, and the dig1t 1 0 would be sent out when the sequence switch S arrives in the third position.

The above 'descrlbed arrangementfor sorting the calls to the toll recording operator, is

longs. This may be seen by looking at Figs.

6 and 7 of the drawings, and it is thought that in View of the explanation above given for calls to the toll recording operator, .it is not necessary to explain in detail. how the calls are sorted out for the express operator, a glance at the drawings be1ng all that is necessary to understand this.

As mentioned before, arrangements have been made for provicing extra battery feed I when a call is trunked to the express operator so as to improvethe transmission at such times, thereby avoiding the useof a special set of trunks.

In order to explain how this is done, it will be assumed that the subscriber at substation A desires to converse with the subscriber at substation B, Fig. 3. Itwill be assumed further that when the subscriber at substation A removes his receiver, the line switch G seizes the repeater R' and the secondary,

switch SS seizes'the directorshown in the drawing. That being the case, when the subscriberdials the number 50 assigned to the express operator, the wipers of the ofiice registerOR are brought into engagement with the tenth setof bank contacts in the fifth level. The first two code digits 9 and 2 are sent out in the usual manner, resulting inthe V selector D, Fig. 2,'being raised to the ninth level to select asecond selector, such as E,

and resulting in the wipers of the selector E being raised to the second'level, whereupon a third selector, such as the selector 1*, is seized i i I V c Since the line of substation A; is an unlimited service'line, armature 18 of the line switch C is not connected up, and relay 602,

Fig. 7, is not energized. Accordingly, when the wipers of the sequence switch S arrive upon the third set of bank contacts at the termination of the second code digit 2, ground is extended over the third contact in the bank of wiper 654i, conductor 523, wiper 513, the bank contact on which 1t 1s standing, the associated IDF umper, conductor 516, normally closed contacts controlledvby armature 633, and relay' 60-1 to battery. Relay 633 thereupon energizes and places a 7 shunt around resistance 638 at armature 631 so as to prepare'a circuit for placing in the above mentioned extra battery feed. As a further result of the energization'of relay 601, it

closes a locking circuit for itself and opens its 

